<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        
        var arr = [];
        var arr2 = [1, 2, 'haha', false];
        var arr3= new Array();
    </script>
    length:返回长度
    push(值):添加一个元素
    splice(起始索引，数量)︰从起始索引开始，删除指定数量的元素
    
</body>
</html>